1. Field of the Invention
This invention relates to telephone apparatuses connected to an Integrated Services Digital Network and methods of controlling same, more particularly, to apparatuses and methods of controlling same, wherein, if a calling operation conflicts with a call-receiving operation, an intention of an operator at a calling side is respected.
2. Description of the Related Art
In a telephone apparatus connected to a public subscriber line or to an Integrated Services Digital Network (hereinafter referred to as the ISDN), by responding to an incoming signal received from the line by an off-hook operation, a speech path is established through which speech is made possible.
In such telephone apparatus, a calling operation conflicts with a call-receiving operation in many occasions. Such conflict occurs, for example, where an incoming signal is received from another telephone apparatus immediately before the operator at the calling side (hereinafter referred to as the caller) conducts an off-hook operation for calling. Under such circumstance, in a conventional telephone apparatus, the off-hook operation is treated as a response to the incoming signal against the intention of the caller because the conventional telephone apparatus has no means for arbitrating such conflict.
For this reason, when the caller dials without recognizing the reception of the incoming signal, a dial tone is transmitted to the destination office, thus discomforting the operator at the destination office. On the other hand, the caller who has been preparing for calling is put into a speech state against his intention, and therefore the caller is also discomforted.
An object of the present invention is to provide a telephone apparatus connected to the ISDN and a method of controlling same, wherein calling processing and call-receiving processing are performed so that the intention of the caller may be respected.